Longwall mining machine

ABSTRACT

A longwall mining machine is described which has cutting rolls pivotally mounted about horizontal axes on a machine housing. The support arms enclose spur gears which are in engagement with each other and are adapted to transmit power from a drive motor in the machine housing to the cutting rolls at the free ends of the support arms. The two outermost spur gears in each arm form a gear pump which pumps the oil accumulating in the outer end of the support arm, when in a downwardly inclined position, back into an oil sump in the machine housing.

United States Patent Lanfermann LONGWALL MINING MACHINE Foreign Application Priority Data Dec. 11, 1969 Germany ..P 19 62 019.0

US. Cl ..299/53, 184/612, 184/628,

Int. Cl. ..E2lc 25/06 Field of Search ..299/5 1-53, 71,

4 1 May 30, 1972 [56] I References Cited UNITED STATES PATENTS 3,219,389 11/1965 Lanfermann ..299/53 3,362,753 1/1968 Sibley ..299/7l X Primary ExaminerErnest R. Purser AttorneyBrown, Murray, Flick & Peckman A longwall mining machine is described which has cutting rolls pivotally mounted about horizontal axes on a machine housing. The support arms enclose spur gears which are in engagement with each other and are adapted to transmit power from a drive motor in the machine housing to the cutting rolls at the free ends of the support arms. The two outermost spur gears in each arm form a gear pump which pumps the oil accumulating in the outer end of the support arm, when in a downwardly inclined position, back into an oil sump in the machine housing.

ABSTRACT 3 Claims, 5 Drawing Figures e as 4 7 Y-l PATENTEDMAY 30 m2 SHEET 10F 13 b, 0 A H,\\ 1b 1 1 N M M m v AQ INVENTOR. WILL Y LANFERMAN/V Attorneys PATENTEDMAY 30 m2 SHEET 30F 3 l/VVEN TOR. W/LLY LANFERMANN BACKGROUND OF THE INVENTION In the mining of coal seams by the mechanized longwall mining method, it is known to employ cutting machines that cut along the longwall face of the coal seam while moving longitudinally along the longwall face on a guideway or track placed therealong. A suitable cutting machine for performing this operation comprises a machine body movable along the guideway, and a pair of support arms pivotally attached to the body and carrying, respectively, two cutting tools or cutting rolls which are hereinafter referred to as upper and lower cutting rolls. As the cutting machine advances along the longwall face, the lower cutting roll works the floor of the coal seam while the upper cutting roll works the upper seam portion, thereby exposing the seam roof.

As will be understood, the pivotal arms on which the cutting rolls are mounted permit them to be adjusted to the desired cutting height. The support arms are hollow and have spur gears mounted therein which transmit the power from the drive motor in the machine housing to the cutting rolls. The power transmitted to the cutting rolls may be up to 300 kilowatts at full load. To transmit such high powers, it has been found necessary to employ a pressurized lubrication system for the spur gears in the support arms and the reduction gearing within the cutting rolls. With this arrangement, the oil is pumped by a pump arranged in the machine housing to the points of lubrication within each cutting roll supporting arm and the cutting roll itself and then collects in the support arm. Dependent upon the position of the support arm, the oil either returns to the oil sump in the machine housing through an opening in the shaft on which the support arm is pivotallymounted, as where the arm is inclined upwardly, or it collects at the outer end of the support arm until its level reaches the opening in the shaft through which the oil flows back to the sump in the machine housing, as when the ann is inclined downwardly. In this latter case, most of the oil used for lubrication is accumulated in the support arm and does not return to the sump and the oil pump. In the support arms, the oil is constantly agitated because of the rotation of the spur gears, and since the oil is not cooled within the support arms, the oil, the spur gears and the reduction gearing within the cutting roll assume intolerably high temperatures.

SUMMARY OF THE INVENTION The present invention provides a simple arrangement in a longwall mining machine of the type described above in which oil is returned to the sump in the machine housing even when the support arms are in their lower positions where the oil normally would not flow back to the oil sump in the machine housing.

According to the present invention, the two outermost spur gears in each support arm form a gear-type oil pump which has connected thereto oil return conduits through which the oil is pumped back to the oil sump in the machine housing.

In one embodiment of the invention, wall members with curved surfaces conforming to the contour of the gears project inwardly into each arm in the space between the outermost two spur gears. An outlet opening is provided at each side of the line of engagement of the outermost gears, each outlet opening communicating with a common return conduit and being selectively connected thereto by a control device. With this arrangement, the pumping action of the two spur gears is independent of their direction of rotation.

The control device may be a piston movable in a cylinder having each of its opposite ends disposed in communication with one of the two aforesaid outlet openings and having at its center an opening providing communication with the return oil conduit leading back to the sump. The piston is then pushed backwardly by the oil entering the cylinder at one side of the piston and the oil is permitted to flow through the opening in the center of the cylinder into the return conduit; whereas the communication path at the other end of the cylinder is automatically blocked by the piston, thereby enabling oil to be returned to the sump regardless of the direction of rotation of the spur gears.

DESCRIPTION OF THE PREFERRED EMBODIMENT The above and other features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIG. 1 illustrates a cutting machine having two cutting rolls and being movably supported on track means extending along a longwall face cut into a coal seam or the like;

FIG. 2 is a top view of the longwall mining machine shown in FIG. 1;

FIG. 3 is a top view of one of the two support arms for the cutting rolls of the machine;

FIG. 4 is a side view of a cutting roll and support ann with portions of the support arm cut away; and

FIG. 5 is a cross-sectional view of the oil control valve of the invention taken substantially along line V-V of FIG. 3.

With reference now to the drawings, and particularly to FIGS. 1 and 2, the longwall mining machine 2 is movably supported on a track structure 1 and cuts the upper portion of a longwall face F with its forward cutting roll 4 and the lower portion of the same face F with its rear cutting roll 3. Each of the cutting rolls 3, 4 is supported by a support arm 5 or 6. During movement of the machine from left to right as viewed in FIGS. 1 and 2, for example, the rolls 3 and 4 are moved along the lower and upper portions of the face F, respectively. The cutting rolls 3 and 4 carry cutting bits 3A and 4A such that as they rotate, they dig into and break up the coal as the mining machine moves along the face F. The cutting rolls 3 and 4 are supported by support arms 5, 6 which are pivotally mounted on shearing drive units 9 and 10 carried on the mining machine body 2. The arms 5 and 6 can be pivotally positioned by hydraulic cylinder and piston assemblies 11 and 12 shown in FIG. 1 which are connected to the pivot arms 5 and 6 through linkages 5A and 6A, respectively. Carried within the machine housing 2 is a drive motor 13 connected through pinion gears 17 and 18 and through spur gearing in the arms 5, 6 hereinafter described in detail, to the cutter rolls 3 and 4.

As is more particularly shown in FIG. 3, the motor 13 is connected through spur gears 14 and 15 and shaft 16 to the bevel gears 17 and 18 carried within the hollow interior of a swivel shaft 8. The bevel gear 18, in turn, is carried on a shaft 19 which carries at its opposite end a pinion gear 20 within the hollow pivot arm 6. The shaft 19 is carried within bearing 42, also disposed within the hollow interior of the swivel shaft 8.

The spur gear 20 transmits the power from the motor 13 to intermediate spur gears 21, 22 and 23 and finally to the spur gear 24 mounted on a shaft 25 which drives the planetary reduction gearing 26 within the cutting roll 4, for example, An oil pump 27 is operatively connected to the spur gear 14 through spur gears 28 and 29 (FIG. 4). As will be understood, an oil pump 27 is associated with each of the two shearing drive units 9, 10, each of which is driven by the motor 13. Each pump 27 is provided with a suction line 30 for pumping oil from a sump 31 through the conduit 32 to an oil cooler 33. A pressure relief valve 34 prevents unduly high pressures within the lubrication system and bleeds oil through conduit 35 to the sump 31 when the pressure becomes too high.

From the cooler 33, the oil passes through conduit 36 and through a sealing ring 37 surrounding the swivel shaft 8 to a passageway 38 connected to a conduit 39 which directs oil to the various points of lubrication (FIG. 4) which are the gears and their bearings, respectively. The oil will then accumulate in the interior 40 of the support arm 6, for example. If the support arm is inclined upwardly as shown in FIG. 4, as when the cutting roll is working the roof of a seam, the oil flows back to the swivel shaft 8 and back into the sump 31 through central opening 41 of the pivot shaft, in which opening is mounted the bearing 42 which supports the shaft 19. When the cutting roll is working the lower portion of the seam as shown by the position of roll 3 in FIG. 1, the support arm is inclined downwardly. In this case, the oil accumulates in the area surrounding the outermost spur gears 23 and 24.

In the area in which the spur gears 23 and 24 engage each other there are provided within the support arm 6, for example, walls 44 (FIG. 4) which closely surround the spur gears such that the oil transported by the teeth of the spur gears into the space or gear pump chamber 48 between the walls 44 is forced into an opening 45 or 49. Assuming that the oil is being forced into the opening 45, it then flows through a connecting channel 46 (FIG. 5) into an oil return conduit 47 and then through the central opening 41 in the swivel shaft 8 back to the sump 31. As shown in FIG. 5, the bore 46 communicating with the opening 45 interconnects the opening 45 with a cylindrical bore 51 which carries a piston 50. A similar bore 46 connects the opening 49 with the cylindrical bore 51. When oil is being pumped from the opening 49 to the return line 47, the piston 50 will be forced into the position shown in FIG. 5, thereby permitting oil to return through conduit 47 but preventing it from passing through the cylindrical bore 51 into the opening 45. Similarly, when oil is being delivered from the opening 45, the piston 50 is moved downwardly as viewed in H6. 5 such that communication is provided between opening 45 and the return conduit 47 while a seal is provided between the opening 49 and the return conduit 47.

It can thus be seen that the present invention provides a system for preventing the accumulation of oil within the support arms 5 or 6 when they are downwardly inclined by utilizing the two outermost spur gears in each support arm as a pump for pumping oil back to the sump associated with that support arm and cutting rolls. Although the invention has been shown and described in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a mining machine having a machine housing, the combination of cutting rolls supported on support arms mounted on the machine housing and pivotal about horizontal axes, said support arms carrying therein spur gears which are in engagement with each other and adapted to transmit power from a drive motor in the housing to a cutting roll carried at the outermost end of the support arm, said support arm having walls projecting from the upper and lower edges thereof into the spaces adjacent the engagement area of the two outermost spur gears, the side walls of the support arm and said projecting walls providing a space between said outermost spur gears to form a gear pump chamber between the two, and an oil return conduit connected to said gear pump chamber for permitting oil to be pumped out of said chamber.

2. The combination of claim 1 wherein the projecting Walls are formed in the space between the two outermost spur gears in each support arm and an oil return passage is connected to the gear pump chamber at each side of the area of engagement of the spur gears, said passage having a central device providing communication with the gear pump chamber at one side of the area of engagement of the spur gears or the other, depending upon the direction of rotation of the spur gears.

3. The combination of claim 2 wherein the spaces adjacent the engagement area of the spur gears are interconnected by a bore having a central section with increased diameter in which an axially movable piston is disposed, the common oil return conduit being connected to the middle of said section with in creased diameter. 

1. In a mining machine having a machine housing, the combination of cutting rolls supported on support arms mounted on the machine housing and pivotal about horizontal axes, said support arms carrying therein spur gears which are in engagement with each other and adapted to transmit power from a drive motor in the housing to a cutting roll carried at the outermost end of the support arm, said support arm having walls projecting from the upper and lower Edges thereof into the spaces adjacent the engagement area of the two outermost spur gears, the side walls of the support arm and said projecting walls providing a space between said outermost spur gears to form a gear pump chamber between the two, and an oil return conduit connected to said gear pump chamber for permitting oil to be pumped out of said chamber.
 2. The combination of claim 1 wherein the projecting walls are formed in the space between the two outermost spur gears in each support arm and an oil return passage is connected to the gear pump chamber at each side of the area of engagement of the spur gears, said passage having a central device providing communication with the gear pump chamber at one side of the area of engagement of the spur gears or the other, depending upon the direction of rotation of the spur gears.
 3. The combination of claim 2 wherein the spaces adjacent the engagement area of the spur gears are interconnected by a bore having a central section with increased diameter in which an axially movable piston is disposed, the common oil return conduit being connected to the middle of said section with increased diameter. 